Conventionally, image readers are used in facsimile machines, copying machines, scanners, banknote checking devices, inspection devices, fingerprint verifying devices and the like. Image readers are used to read various types of object-to-be-reads such as manuscripts, books, pages of a magazines, documents, paintings, photographs, transparent positives, rolls of film, banknotes, securities, circuit boards, electronic components and fingerprints. In addition, image readers receive reflected light from the object-to-be-read through sensor elements, i.e. photosensitive elements, thereby obtaining the image of the object-to-be-read. The reflected light from the object-to-be-read includes not only visible light but also light with wavelengths other than those of the visible light. Hence, the types of the light source incorporated in the image reader or provided external to the image reader, i.e. the light source used for emission of light to illuminate the object-to-be-read and to obtain reflected light, include not only types that emit visible light but also types that emit light of non-visible wavelengths.
If the light source is incorporated in the image reader, light is emitted from light-source elements (point light sources) such as LEDs or organic EL elements, the emitted light is guided through the interior of a light guide (light guiding member) formed of a transparent material (transparent member) such as a resin, and the guided light is emitted to illuminate the object-to-be-read (see, for example, Patent Literatures 1 to 7). Needless to say, there are also light sources that have no light guide. Regardless of the presence/absence of the light guide in the light source, there are also image readers that have no built-in light source (see, for example, Patent Literature 8) and that can use such a light source.
Patent Literatures 1 and 2 disclose image readers in which the light guide and the lens array are in contact with each other. Patent Literatures 2 and 3 disclose image readers in which the light guide is integrated with a transparent top panel (guide plate) along which the object-to-be-read passes after having been fed in the feeding direction (sub-scanning direction). Patent Literatures 4, 5, 6 and 8 disclose image readers that have a board formed with imaging elements and fastened by attachment members (elastic members) or screws. Still further, Patent Literature 7 discloses an image reader that includes a board having imaging elements disposed on a light guide.